Ribautia cf. paucipes Attems, 1952

Fig. 5

Examined material.

NHMUK 015991467, 1 juvenile, Casuarina litter, Picard, Aldabra, 10. 12. 1974, leg. V. W. Spaull.

Remarks.

The sexually immature specimen found in the present sample displays all diagnostic characters that support its assignment to Ribautia, comprising an elongate cephalic shield, lack of lappets on the first maxillae, the two halves of the second maxillary coxosternite being united by a sclerotised isthmus and the pleural sutures of the forcipular coxosternite being parallel to its lateral edge distally. A potentially novel ontogenetic observation is the incomplete separation of the two halves of the second maxillary coxosternite by an isthmus (Fig. 5 B), as is a characteristic of Ribautia. Taking into account the very small size (length 7 mm) and sexual immaturity of the specimen, this may be a character state that becomes more conspicuous in older individuals.

Beside the very low number of leg-bearing segments (37), which is shared with R. cf. paucipes reported from the Seychelles (Bonato and Minelli 2010), the developmental stage of the present specimen does not allow for satisfactory evaluation of potential morphological differences between Ribautia specimens described from Western Indian Ocean localities and type material of Ribautia paucipes described from the environs of Lake Kivu in Central Africa. Notably, the Aldabra specimen lacks evident denticles on the anterior margin of the forcipular coxosternite and the interior margin of the forcipular trochanteroprefemur, although these are clearly illustrated in the original description of R. paucipes (Attems 1952: fig. 203). The specimen also lacks conspicuous coxal organs or coxal pores, a character state not noted in R. cf. paucipes recorded from the Seychelles. Ontogenetic variation in the number of coxal pores has been well-documented for other geophilid centipedes (Horneland and Meidell 2009; Gregory and Barber 2010; Brena 2014; Stojanović et al. 2020), increasing with body size at each postembryonic stage, and being absent in comparably sized adolescens stages of some species (Gregory and Barber 2010). Additionally, the second maxillary pretarsus of the present specimen is markedly shorter and less acuminate than illustrated for R. paucipes from continental Africa. As the ontogenetic variation of the morphology of the second maxillae in Ribautia is not presently known and in other characters the specimen strongly resembles individuals described from the Seychelles, we maintain its presently assigned identity.